Indexing mechanism for sheet feeding means



1964 D. w. HUBBARD ETAL 3,154,233

INDEXING MECHANISM FOR SHEET FEEDING MEANS 2 Sheets-Sheet 1 Filed Dec. 3, 1962 INVENTORS. DAVID W. HUBBARD HENRY R. COFEK ATTORNEY 1964 D. w. HUBBARD ETAL 3,154,233

INDEXING MECHANISM FOR SHEET FEEDING MEANS 'Filed Dec. 3, 1962 2 Sheets-Sheet 2 73 FIG. 2

EXTERNAL LINE SPACE DAVID W. HUBBARD CONTROL HENRY R. COFEK FIGS 0 v Z ATTORNEY United States Patent 3,154,233 EEEXING MECHANISTVI FQR SHEET FEEBlNG MEANS David W. Hubbard, Stamford, and Henry R. Cofek,

Fairfield, onn., assignors to Sperry Rand Corporation,

New York, N.Y., a corporation of Eelaware Filed Dec. 3, 1952, Ser. No. 241,796 10 Gators. (l. 226-9) This invention relates generally to sheet feeding mechanism having a plurality of driven members simultaneously engaging a sheet for advancing the sheet in line spacing increments, the invention more particularly relating to the driving mechanism for said members which includes means adjustable for enabling the indexing of the sheet relative to a work station and for maintaining a desired tension on a sheet while being fed.

The invention is disclosed herein in an embodiment adapted for driving the paper feed tractors of a high speed printer. Machines of this class are ordinarily equipped with a plurality of tractors provided with sprocket teeth adapted to engage with sprocket holes running along the marginal edges of a form to be fed. It has been found that, when the form being fed comprises multi-part sheets interleaved with sheets of carbon or other transfer means, correct registration of all parts of the form with the printing mechanism requires the provision of a pair of tractors on both sides of the print station, i.e. above and below the print station. The provision of tractors on both sides of the print station enables the longitudinal tension of the feeding forms to be regulated to avoid the separation of the sevenal parts of the the form at the print station and to prevent the development of any air pockets between the several parts of the form. The provision of tractors on both sides of the print station for the reasons above mentioned necessitates the provision of tractor driving means for openating both pairs of tractors in unison and so designed that the stresses incident to the rapid acceleration and deceleration of the tractor mechanism in high speed line spacing operation does not increase the longitudinal tension on the form so as to run the risk of tearing.

In accordance with the invention, the tractor mechanism is driven from a constantly operating power source through a clutch, operating in conjunction with a brake and controlled to advance the paper in line space increments. An indexing drum and associated reluctance head mounted on one of the tractor drive shafts generates signals for controlling the clutch and drum to determine the proper indexing of the form at successive line space positions. The clutch is associated directly with the shaft for driving the pair of tractors below the print station, hereinafter referred to as the rear pair of tractors, and the brake and indexing drum are directly associated with the shaft for driving the pair of tractors above the print station, hereinafter referred to as the forward pair of tractors. A drive belt couples the respective drive shafts for rotation in unison. This relative disposition of the brake and clutch on respective shafts coupled together by a drive belt avoids the risk of imparting excessive tension on the form during rapid acceleration and deceleration of the mechanism, since the belt absorbs the initial shock of the braking action thereby assuring that the rear tractors will not be arrested prior to the forward tractors in braking operation and, furthermore, absorbs the driving shock in accelerating action by assuring that the forward tractors will not be driven prior to the drive of the rear tractors.

Means are provided for adjustably setting the reluctance head relative to the indexing drum, this means being connected with the brake mechanism so as to enable an indexing adjustment to be made when the brake is 3,154,233 Patented Oct. 27, 1964 energized and effective. Means are also provided for adjusting the longitudinal tension of the paper form, this latter adjustment being effected through adjustable roller means which alter the orbital path of the driving belt thereby altering the relative rotational position of the respective drive shafts.

It is therefore an object of the invention to improve upon the means for driving sheet engaging members to efiect line spacing feed of the sheet.

It is a further object of the invention to provide improved means for adjusting the indexing of a sheet within a line space position.

It is a further object of the invention to provide means for adjusting the longitudinal tension in a sheet engaged by a plurality of sheet feeding members arranged at successive locations in the path of sheet feed.

Further objects of the invention together with the features contributing thereto and the advantages accruing therefrom will be apparent from the following description when read in conjunction with the drawing wherein:

FIG. 1 is a view in side elevation of the left-hand side of a high speed printer showing the paper feed drive mechanism.

FIG. 2 is a front sectional view taken along the line 22 of FIG. 1.

FIG. 3 is a detail sectional view of the adjustable registration control mechanism taken along the line 3-3 of FIG. 2.

FIG. 4 is a detail sectional view of the adjustable tension control mechanism taken along the line 44 of FIG. 2.

PEG. 5 is a diagram illustrating the functional control by the indexing mechanism over the clutch and brake means of the driving mechanism.

The feeding mechanism operates to advance in line space increments a sheet of paper or the like, which may comprise a single ply or multi-part form, between a row of type hammers ll suitably supported in a type head assembly 12 and a print drum 13, which stage in the feed path may be considered to be the printing station. The sheet 10 is preferably formed with sprocket holes 14- extending along each side margin of the sheet for engagement by the sprocket pins 16 of a plurality of paper feeding tractors 15. The tractors may be of any there being one pair, of which one is shown in FIG. 2, suitable design and construction and are provided in pairs, there being one pair, of which one is shown in FIG. 2, disposed above the printing station which is the more advanced location of the feed path since the feeding direction of the sheet is upwards past the printing station. Another pair of tractors 15, of which one is shown in FIG. 2, is disposed below the printing station at a less advanced point in the feeding path of the sheet. The upper tractor is mounted on an upper tractor drive shaft 20 and an upper support shaft 21. The support shaft 21 extends between the side frames 22 of the ma chine of which only one is shown in FIG. 2. The tractor drive shaft 2% is preferably of square cross-section and has each end thereof terminating near a side frame of the machine in a coupling 23, the left-hand coupling serving to join the drive shaft 29 with an extension of the drive shaft of rounded configuration suitably journaled in the side frame plate 22 by means of a bearing 24.

The lower tractor 15 is similarly mounted on a lower drive shaft 30 and a lower support shaft 31 similarly extending between the side plates of the machine. The lower drive shaft 30 like the upper drive shaft 20 is squared and terminated at its left-hand end in a coupling 33 joining the shaft with an extension 35 suitably journaled in the side frame 22 by means of a bearing 34.

Preferably each tractor is provided with a pivotal pressure plate 36 swingable into overlying relation with the (J sheet to hold the sheet in engagement with the sprocket pin 16. Each tractor also preferably includes a latch lever 37 operable for clamping the respective tractor to its supporting shafts and releasable to enable the tractor to be slideably adjusted along the shafts for accommodating forms of different width and for registering the forms with the printing station.

The provision of tractor devices both before and behind the printing station has been found to greatly improve the registration of the sheet material at the printing station, particularly when the sheets comprise multi-part forms. A further advantage in employing the several tractors in this manner is that it thereby enables a pre determined longitudinal tension in the sheet at the printing station for which, in the case of multi-part forms, prevents pockets of air bubbles from forming between the several form parts which would have a detrimental effect on the printing density. However, the provision of the several tractors which operate intermittently to feed the paper in line space increments requires the provision of separate drive mechanisms which must not at any time get out of phase in such a manner as to increase the tension on the feeding sheet to the point of tearing.

The means for driving the tractors in the present instance includes a motor 40, see FIG. 1, having a drive pulley 41 connected by a belt 42 with the drum shaped housing 43 of a drive clutch 45. The clutch housing 43 is supported for rotation about the hub of a clutch armature 46 which is securely fastened to the lower drive shaft 35, the outer end of which is carried in a bearing 47 supported in an extension 48 of the side frame member 22. The clutch housing 43 is formed with an annular recess in which is wound a clutch coil 50, the terminals of which coil are connected to a printed circuit commutator 51 secured to the outer face of the housing 43 and which through the means of brushes, not shown, provides the means for connecting the coil to a control circuit. Energization of the coil 50 forces the clutch housing 43, the inner face of which is provided with a ring 52 of friction material, into frictional driving engagement with the armature 46 thus transmitting the torque of the motor to the drive shaft 35. Alongside of the armature 46 is a drive pulley 55 around which is wrapped a flexible belt 56 which extends upwardly and reaches around a pulley 57 secured fast to the upper tractor drive shaft 25. Formed integrally with the pulley 57 is an indexing drum 60 which rotates with the shaft and serves to generate a train of signals indicative of the line space position of the sheet material being fed. Cooperating with the indexing drum 60 is a reluctance head 61 carried by a drum shaped head support 62 mounted on a bearing 63 and including on its side face a retainer disc 64. In the present instance the drum 60 is formed with a series of perforations at predetermined spaced intervals which correspond to line space positions of the sheet being fed. The perforations align with the reluctance head 61 and cause increased reluctance in the head when advanced past the head gap to cause a control signal to be generated by the head winding. The reluctance head, in effect, detects or reads the perforations. The control signals may be utilized for stopping the sheet feed at the corresponding line position by de-energizing clutch 45 and energizing a brake means hereinafter to be described.

Mounted on the shaft 25 alongside the reluctance head support drum 62 is the armature 71 of a magnetic brake 70, the armature comprising a disc shaped member having an elongated hub which is secured fast to the shaft 25. Mounted for rotation about the hub of the armature on suitable bearing material is a brake housing 72 formed with an annular recess in which is wound a brake coil 73. The inner face of the brake housing is fitted with a ring 74 of friction material disposed for contact with the brake armature 71. A compression spring 75 fitted between an auxiliary frame bar 76 of the machine and the brake housing maintains a light lateral thrust on the housing to maintain the housing in close gap relation to the armature but which thrust is insufiicient to stop the rotation of the armature as long as the clutch mechanism is engaged. A hearing 77 fitted in the frame bar 76 supports the outside end of the shaft 25. It will be apparent that when the brake coil 73 is energized the magnetic attraction between the housing and the armature will hold the friction ring 74 in firm contact with the armature to thereby in effect couple the housing with the shaft 25. Therefore, when the brake is energized any rotative adjustment of the housing will cause a corresponding rotative adjustment of the angular position of the shaft 25. This in turn will angularly displace, to a corresponding extent, the indexing drum 60 and will also operate the paper feed tractors 15 so as to adjust or index the line space position of the form carried by said tractors relative to the printing station. The rotative adjustment of the brake housing 72 as just described for indexing purposes does not alter the angular relation between the indexing drum 6% and the pick-up head 61 since means are provided to also rotatively adjust the pick-up head a corresponding extent.

Secured to the bottom of the brake housing 72 is a depending arm 80 the lower end of which is bifurcated so as to form a pair of tines separated by a central elongated slot. The upper portion of said arm 80 is connected to the reluctance head support drum 62 by means of a tie link 81 suitably secured by screws or the like to the arm 80 and to the retainer disc 64 attached to the reluctance head support drum. As can be seen best in FIG. 3, the tie link 81 is in the form of a fiat elongate member and is so oriented that its width lies in a plane perpendicular to the axis of shaft 25 and its thickness extends in a direction parallel with the axis of shaft 25. Accordingly the link 81 is effective for unyieldingly coupling the arm 80 with the retainer disc 64 so as to rotatively adjust the reluctance head support drum 62 in response to the rotative adjustment of the brake housing 72. The relative thinness of the link 81, however, affords a limited amount of pliability along a line parallel to the shaft 25 enabling the brake housing to laterally shift into and out of effective braking engagement with the brake armature under the influence of its coil 73 as heretofore described.

For manually adjusting the rotative position of the brake housing and the reluctance head support drum a cylindrical stud 82 is freely supported in the side walls of an open limit block 83 adapted to engage and limit the lower extremity of the arm 80. Said stud is tapped to receive a threaded rod 84 which extends through the stud and through the slot between the tines of the arm 80 and is journaled at one end in a subframe panel 85 and at its other end in a subframe panel 86, said frame panels being suitably secured to the side frame 22 and being means for supporting the auxiliary frame bar 76. Mounted on the front end of the rod 84 is a control knob knob 87 which is conveniently accessible to the operator of the machine and by which the rod may be turned in one direction or another to limit the arm 80 at a corresponding adjusted position. A stud 88 carried by the arm 80 and fitted in a recess formed in the limit block 83 prevents the block from turning with the rod 84. A spring 89 stretched between the arm 80 and the front frame panel 86 biases the arm 80 into limiting engagement with the block.

It will be apparent from the foregoing that indexing adjustment achieved by rotation of the control knob 87 may be accomplished either while the machine is operative, feeding sheets past the printing station, or when the feeding mechanism is inactive. In the latter case, assuming that power to the machine is turned on, the clutch 45. will be disengaged and the brake 70 will be engaged. Accordingly, operation of the control knob 87 under these ment of the brake housing 72 and the reluctance head support drum 62 and, since the shaft 25 is coupled to the brake housing, the indexing drum 60 will also be rotatively adjusted along with the adjustment of the tractors which will position the form sheet at the selected index point of a line space position. Since the sheet form is either advanced or withdrawn by operation of the control knob 87, it enables the operator to visually check, by means of any suitable scale means with which the machine may be equipped, the index point selected by operation of the control knob. If the control knob is operated while the paper feeding mechanism is active, the brake 70 will be disengaged so that the effect of the adjustment will be to reposition the brake housing 72 and the reluctance head support drum 62 so that subsequent signals will be generated by the reluctance head 61 at that point of form sheet travel corresponding to the selected index position.

As heretofore mentioned, one of the objectives in providing paper feeding tractors on opposite sides of the print station is to enable the longitudinal tension of the sheet material to be maintained at a selected degree. The means for selecting the degree of tension on the sheet material is associated with the belt 56 coupling the shaft 35 with the shaft and includes an idler roller 90 carried by a triangular shaped lever 91 formed at one end with a hub pivotally mounted on a pivot stud 92 secured in the side machine plate 22. As can be seen best in FIG. 1, the idler roller 90 bears against the inner reach of the belt 56 and may be adjusted by the pivoting of the support lever 91 over an arc intersecting the belt orbit to vary the effective length of the inner reach of the belt. The adjustment is effected by means of a manually rotatable rod 93 threaded into a suitably tapped cylindrical stud 94 and mounted in the subframe panel 86, the end of the rod carrying control knob 95. The rod 93 is supported in a thin bushing 96 overlying an oversized aperture .in the frame panel 86 so as to enable a slight amount of axial deviation of the rod 93 as is required in adjusting the lever 91 about its pivot stud 92. The stud 94 is freely mounted in a hub 97 slotted to receive the rod 93 and permitting the stud to turn within the hub 97 due to the arcuate path of movement for the stud.

In order that the tension in the belt 56 may be maintained constant regardless of the adjustment setting of the idler roller 90 another idler roller 101 is associated with the belt, see FIG. 1, the latter roller being carried at one end of a lever 102 pivoted to the side machine frame 22. A spring 103, preferably of the constant force type, stretched between the arm 102 and an anchor point on the machine frame urges the roller 101 into engagement with the outer reach of the belt 56 to assure that the tension of the belt 56 is maintained at a predetermined degree regardless of the adjusted setting of the roller 90.

Adjustment of the tension-ing mechanism may be effected while the paper feeding mechanism is active or inactive. It will be apparent that when the paper feed mechanism is inactive, with the clutch 45 disengaged and the brake 70 engaged, adjustment of the position of the roller 90 in a direction to increase the inner reach of the belt will cause a corresponding angular displacement of the lower tractor drive shaft relative to the upper tractor drive shaft 25 to thereby cause the tension in the sheet material 10 to be increased. Likewise, adjustment of the roller 90 in the other direction to shorten the inner reach of the belt 56 will vary the angular relation of the shaft 35 relative to the shaft 25 so as .to decrease the tension in the sheet material being fed. When the adjustment is made at a time that the feeding mechanism is active, the clutch will be engaged and the brake 70 will be disengaged whereupon any change in the condition of the idler roller 90 by operation of the control adjustment knob 87 will result in angularly displacing the tractor drive shaft 25 relative to the drive shaft 35 to similarly result in a corresponding change in the tension of the sheet material being fed by said tractor.

FIG. 5 illustrates in a general way the manner in which the clutch and brake are controlled to effect the desired progress of the sheet material past the printing station. The signal generated by the indexing drum 60 is utilized in an external control unit 98, which may be incorporated within a computer or the like, as a reference signal indica-ting when the sheet material has advanced an extent corresponding to one line space position. If the mechanism is programmed to perform a single line spacing operation, this signal is relayed by any suitable means to simultaneously de-energize the coil 50 of clutch 45 and energize the coil 73 of brake 70. If the machine is programmed to space a predetermined number of line spaces, the signal generated by the indexing drum is not relayed to control the clutch and brake but may instead activate a counting mechanism in the control unit 98 for determining the number of line space positions over which the sheet material is to be continuously fed before a signal is relayed to disengage the clutch and activate the brake. The signals for activitating the feeding mechanism by energizing the clutch 45 and de-energizing the brake are automatic functions of a print cycle and are generated and relayed to the clutch and brake under control of the external control unit 98 when the equipment has completed the printing of a selected line space position and the program calls for paper advance to another line space position.

While there has been shown and described what is considered to be a preferred embodiment of the invention it is of course understood that changes in form could be made without departing from the spirit of the invention, and it is therefore intended that the invention be not limited to the exact form herein shown and described nor to anything less than the whole of the invention as hereinbefore set forth and as hereinafter claimed.

What is claimed and desired to be secured by Letters Patent is:

1. In a sheet feeding mechanism for advancing sheet material through a work station,

(a) a plurality of feed members disposed serially along the feed path and each having means for engaging sheet material stretched therebetween to advance same through the work station,

(1)) a first rotatable member for driving the feed member disposed at a more advanced position along the feed path,

(c) a second rotatable member for driving the feed member disposed at a less advanced position along the feed path,

(d) a motive power source for driving said first and second rotatable members,

(e) a clutch device operable for connecting said power source to said second rotatable member,

(1) flexible means coupling said first and second r0- tatable members for joint operation, and

(g) a brake device operable in mutually exclusive relation to said clutch device for absorbing the inertia of said first rotatable member when said clutch device is disengaged, whereby said flexible means transmits the driving force of the clutch to said first rotatable member and the drag of said brake device to said second rotatable member to prevent increase in the longitudinal tension of the sheet material stretched between said serially arranged feed members.

2. The invention according to claim 1 wherein said clutch device is mounted on said second rotatable member and is magnetically actuated for operatively connecting said second rotatable member with the said power source.

3. The invention according to claim 1 wherein said brake device is mounted on said first rotatable member and is magnetically actuated to absorb the inertia of said first rotatable member.

4. The invention according to claim 1 wherein said flexible means comprises a belt formed of resilient material and drawn about belt engaging members integral with each of said first and second rotatable members.

5. The invention according to claim 1 wherein said feed members comprise tractors presenting sprocket pins en-' gageable with sprocket holes formed in the said sheet material.

'6 In a sheet feeding mechanism for advancing sheet material in intermittent steps through a succession of line space positions relative to a work station,

(a) a plurality of feed members disposed serially along the feed path and each having means for engaging the sheet material stretched therebetween to advance same to the next line space position,

(b) a first rotatable member for driving the feed member disposed at a more advanced position along the feed path,

() a second rotatable, member for driving the feed member disposed at a less advanced position along the feed path,

(11') a motor for driving said rotatable members,

(e) a clutch device operable for connecting said motor to said second rotatable member,

(1) means coupling said first and second rotatable members for joint operation,

(g) a brake device operable in mutually exclusive relation to said clutch device for absorbing the inertia of said first rotatable member when said clutch device is disengaged,

(h) indexing means driven in unison with said rotatable members for generating control signals for deactivating said clutch device and activating said brake device, and a (i) manually operable means for adjusting said indexing means to efiFect a corresponding adjustment of the alignment of the line space'position of said sheet material relative to said work station.

7. The invention according to claim 6 wherein said indexing means comprises an indexing drums carried by said first rotatable member and a reading head adjacent thereto and mounted for rotative adjustment through an arc concentric to the axis of said drum, said adjustment means being manually operable to vary the angular relation between said reading head and said drum to cause a corresponding variance in the sheet feed position at which is generated the control signals for said clutch device and said brake device.

8. The invention according to claim 7 wherein said brake device is rotatively adjustable to vary the angular position of said first rotatable member and is coupled to said reading head for concurrent adjustment therewith by said adjusting means, whereby the operation of said adjustment means when said brake is energized operates to advance said sheet material into a corresponding adjusted alignment relative to said work station. 7

9. The invention according to claim 8 wherein said brake device includes an armature fastened on said first rotatable member and a coil housing supported for rotative adjustment within an arc concentric to the axis of said first rotatable member. a

10. The invention according to claim 9 wherein said coil housing is mounted for laterial movement along the axis of said first rotatable member into and out of frictional contact With said armature under control of the coil contained in said coil housing.

Rayburn Nov. 28, 1950 Wilkins Aug. ,14, 1962 

1. IN A SHEET FEEDING MECHANISM FOR ADVANCING SHEET MATERIAL THROUGH A WORK STATION, (A) A PLURALITY OF FEED MEMBERS DISPOSED SERIALLY ALONG THE FEED PATH AND EACH HAVING MEANS FOR ENGAGING SHEET MATERIAL STRETCHED THEREBETWEEN TO ADVANCE SAME THROUGH THE WORK STATION, (B) A FIRST ROTATABLE MEMBER FOR DRIVING THE FEED MEMBER DISPOSED AT A MORE ADVANCED POSITION ALONG THE FEED PATH, (C) A SECOND ROTATABLE MEMBER FOR DRIVING THE FEED MEMBER DISPOSED AT A LESS ADVANCED POSITION ALONG THE FEED PATH, (D) A MOTIVE POWER SOURCE FOR DRIVING SAID FIRST AND SECOND ROTATABLE MEMBERS, (E) A CLUTCH DEVICE OPERABLE FOR CONNECTING SAID POWER SOURCE TO SAID SECOND ROTATABLE MEMBER, (F) FLEXIBLE MEANS COUPLING SAID FIRST AND SECOND ROTATABLE MEMBERS FOR JOINT OPERATION, AND (G) A BRAKE DEVICE OPERABLE IN MUTUALLY EXCLUSIVE RELATION TO SAID CLUTCH DEVICE FOR ABSORBING THE INERTIA OF SAID FIRST ROTATABLE MEMBER WHEN SAID CLUTCH DEVICE IS DISENGAGED, WHEREBY SAID FLEXIBLE MEANS TRANSMITS THE DRIVING FORCE OF THE CLUTCH TO SAID FIRST ROTATABLE MEMBER AND THE DRAG OF SAID BRAKE DEVICE TO SAID SECOND ROTATABLE MEMBER TO PREVENT INCREASE IN THE LONGITUDINAL TENSION OF THE SHEET MATERIAL STRETCHED BETWEEN SAID SERIALLY ARRANGED FEED MEMBERS. 